IP₃R, store-operated Ca²⁺ entry and neuronal Ca²⁺ homoeostasis in Drosophila

The IP₃R (inositol 1,4,5-trisphosphate receptor) releases Ca²⁺ from the ER (endoplasmic reticulum) store upon binding to its ligand InsP₃, which is thought to be generated by activation of certain membrane-bound G-protein-coupled receptors in Drosophila. Depletion of Ca²⁺ in the ER store also activates SOCE (store-operated Ca²⁺ entry) from the extracellular milieu across the plasma membrane, leading to a second rise in cytosolic Ca²⁺, which is then pumped back into the ER. The role of the IP₃R and SOCE in mediating Ca²⁺ homoeostasis in neurons, their requirement in neuronal function and effect on neuronal physiology and as a consequence behaviour, are reviewed in the present article.